2014 RXV conversion to LiFePO4

[bdserv]

I have more or less completed the conversion of my 2014 RXV over to LiFePO4 cells using a DIY pack. I have one or two loose ends to finalize but I can begin running the cart to see how the cells and the cart perform.

The cells I purchased from Mike over on the DIY solar forum. They are 150 AH cells with a 3C rating.



The tray after removal of the FLA batteries. I drilled 4 holes in the rails that the FLA batteries sit on to hold the battery enclosure in place.



The bottom of my enclosure base plate. The small wood strips are mounted with construction adhesive and screws, and they mate with the ridges in the tray to add side-to-side and front-back stability to the mounting arrangement.



The enclosure is constructed of 3/4-in plywood. You can see the t-nuts that are countersunk into the base plate for the bolts that will come up through the holes I added in the tub rails to hold the enclosure in place.



Batteries installed after top balancing and side panels are in place. The batteries are separated from each other as well as the sides using 2 mm closed cell foam. The cells are under light compression and cannot be moved or removed once the enclosure sides are in place.



Top rails in place.



BMS mounted and wired.



Completed assembly with terminal bolts for connections to golf cart. Rope handles are there to make it easier to lower assembly into battery tub.



Installed in cart. Still enough room for my under seat tray.



Weight of assembly is about 120 lbs. Total cost for everything was just under $1200.00 not including the nice Fluke DVM I bought and the benchtop power supply for top balancing, both of which I needed anyway.

[badandyturbo]

Nice.

[Volt_Ampere]

Nice! Much better than the drop-in stuff IMO. I might consider this for my next build. Don't know when that will be though.

[PingEye3]

Originally Posted by bdserv

I have more or less completed the conversion of my 2014 RXV over to LiFePO4 cells using a DIY pack. I have one or two loose ends to finalize but I can begin running the cart to see how the cells and the cart perform.

The cells I purchased from Mike over on the DIY solar forum. They are 150 AH cells with a 3C rating.



The tray after removal of the FLA batteries. I drilled 4 holes in the rails that the FLA batteries sit on to hold the battery enclosure in place.



The bottom of my enclosure base plate. The small wood strips are mounted with construction adhesive and screws, and they mate with the ridges in the tray to add side-to-side and front-back stability to the mounting arrangement.



The enclosure is constructed of 3/4-in plywood. You can see the t-nuts that are countersunk into the base plate for the bolts that will come up through the holes I added in the tub rails to hold the enclosure in place.



Batteries installed after top balancing and side panels are in place. The batteries are separated from each other as well as the sides using 2 mm closed cell foam. The cells are under light compression and cannot be moved or removed once the enclosure sides are in place.



Top rails in place.



BMS mounted and wired.



Completed assembly with terminal bolts for connections to golf cart. Rope handles are there to make it easier to lower assembly into battery tub.



Installed in cart. Still enough room for my under seat tray.



Weight of assembly is about 120 lbs. Total cost for everything was just under $1200.00 not including the nice Fluke DVM I bought and the benchtop power supply for top balancing, both of which I needed anyway.

Nice Work!!

[Pat911]

Yep, much better than the drop ins and fully serviceable.

[bdserv]

Thought I would follow up with an update.

It's been about 3 months since installation and the pack has been essentially trouble free. My routine is to charge after [5] 18-hole rounds and based on the aH required from the charger to top them off they are only down to about 45% after 5 rounds. Based on that, I only need to charge about once a week which means this pack will easily outlive the cart even if I only get half the cycle life advertised.

I am using a DPI Gen IV charger in SLA mode and I modified it to include a supervisory circuit to disconnect the charger when the pack reaches 90% SOC. This eliminates the single-point failure risk of relying on the BMS alone to monitor charge progress.

Overall I am very happy with the change to LiFePO4 and these particular cells, but I cannot recommend the supplier I mentioned above since it appears that quite a few problems have occurred with deliveries over the past several months since I received mine. I guess I was lucky in that regard.

[davidgolfer]

Originally Posted by bdserv

Thought I would follow up with an update.

It's been about 3 months since installation and the pack has been essentially trouble free. My routine is to charge after [5] 18-hole rounds and based on the aH required from the charger to top them off they are only down to about 45% after 5 rounds. Based on that, I only need to charge about once a week which means this pack will easily outlive the cart even if I only get half the cycle life advertised.

I am using a DPI Gen IV charger in SLA mode and I modified it to include a supervisory circuit to disconnect the charger when the pack reaches 90% SOC. This eliminates the single-point failure risk of relying on the BMS alone to monitor charge progress.

Overall I am very happy with the change to LiFePO4 and these particular cells, but I cannot recommend the supplier I mentioned above since it appears that quite a few problems have occurred with deliveries over the past several months since I received mine. I guess I was lucky in that regard.

Very nice! I have a similar results with my 150ah battery from extreme team. I didn't feel comfortable enough building a battery pack like you did. I'm getting about 18 holes per 10% of battery. Similar to you 5-6 rounds then I charge usually down to 30% before I charge.

[reiter284]

Are you running everything through the BMS? I don’t see any relays.

If so which BMS are you using and are your controller and tires stock?

[bdserv]

Originally Posted by reiter284

Are you running everything through the BMS? I don’t see any relays.

If so which BMS are you using and are your controller and tires stock?

I am using a common port 30A JBD BMS wired so that charging current flows through the BMS but not discharge current. Instead, the discharge MOSFETs control a relay which controls an audible alarm that sounds when any cell drops below 3.1v to let me know it is time to head home. This never happens though since I can get 5 rounds of 18 holes without going below about 35% SOC and I don't push it beyond that before charging.

Controller is the stock Curtis for a 2014 RXV and tires are 20.5-in.